Sunday, March 10, 2013

Sunday Photo(s)

As I think I've mentioned before, I wasn't too interested in my new camera's big zoom lens when I bought it. I was really more interested in having better low light performance, and a bit better anti-shaking performance as well. Of course, now I use the zoom lens all the time.

Last weekend at Redondo, I saw a lot of airplanes passing overhead, since SeaTac Airport is a few miles north. Thanks to the zoom lens, I was able to photograph some of the bigger airliners in high enough resolution to see their registration numbers.

So now I can identify aircraft more precisely, which is good. For instance, this is Alaska Airlines' Boeing 737-800 N581AS:

Image credit: All photos by Cujo359

Even at this distance, I find it hard to tell the difference between this model of 737 and the previous generation of stretched 737, the 737-400. The finlets aren't a spotting feature, because they can be retrofitted, and often are.

It looks pretty much like -600s and -700s do, except for having no finlets.

Of course, in this view you can also see the flaps and spoilers deployed on the wings. When an aircraft is landing, these are used to change the amount of lift the wing provide. When fully deployed, they'll both help provide lift and slow the plane down, so the plane can get onto the ground. They're also used on takeoff, but in a different position, as Lufthansa Airbus 330-300 D-AIKJ illustrates here:

During and after takeoff, the plane isn't going fast enough for the wings to provide the lift needed. The flaps (at the back of the wing) and the slats augment lift by exaggerating the wing's airfoil, which increases lift. Once the plane is moving faster, the flaps and slats are retracted.

Looks pretty much like the Southwest Airlines -300, doesn't it? The only difference I can spot is the squared-off fairing on the -300, which was a pretty common feature on those models. I don't know if that's definitive, though, because there are lots of options on every model of airliner. (see NOTE 1).

Just to counter accusations of favoritism, here's another Airbus, United Airlines A320 N411UA,

Airbuses have different cockpits and tail shapes from Boeings. That's the easiest way I've found to tell them apart.

As always, click on the pictures to enlarge, and have a good Sunday.

UPDATE/Afterword: I forgot to mention that I've processed these photos a bit to enhance the contrast and eliminate some of the noise. Last week's Sunday photos are mostly unprocessed. All of these photos were taken at or near full zoom, which is the 20X factor, or about 90 mm focal length.

NOTE 1: Anyone who follows those links identifying the individual aircraft will note that the model numbers are somewhat different from the ones I've used. That's because each airline gets to specify lots of options when it orders airliners, from engines to interior design. Each individual combination of options got its own individual "sub-model" number when I worked at Boeing many years ago. I suspect that's still the case, but there are many variants of one particular airliner, and that's why the discrepancy exists between the Planespotters.net model identifications and what I wrote here.

Sorry about the captchas - I don't think there's anything I can do about them.

Except possibly for the last aircraft, all of the images are at full zoom. It's a 20X zoom, according to the EXIF data in the photos, that's 4.5 to 90 mm focal length, which makes all of these photos taken at 90mm.

Except for the zoom number, that information is available in the photos in the EXIF data.

I'm bad at judging distances in the air. My guess is that on takeoff they're maybe 2000 ft. in the air by the time they're over Redondo, and maybe 1000 ft. up on landing. They're often above the clouds already on takeoff, if the ceiling is as low as it can be here on typical winter days.

The focal length is indeed 90mm, but that's not informative unless you know the size of the sensor. I took the liberty of importing one photo into Picasa, which informs me that 90mm on your Canon is equivalent to 523mm on a 35mm camera. Since standard lenses for 35mm are about 50mm, that means your photos are taken at about a 10 times magnification compared to the standard.

No worries, One Fly. I don't like the captchas, either, but it's them or spam, so I always feel a bit guilty. Meanwhile, don't forget that Ctrl-+ magnifies the page.

Thanks for the insight, David Evans. You've hit on one of the reasons I try to avoid talking about zoom factors without some other qualifier. Subjectively, minimum zoom on the camera looked to show a wider perspective than what I saw with my own eyes, and maximum zoom shows quite a bit more than the naked eye, and at least twice what my old digital camera did.

And thank goodness for miniaturization. A 520 mm lens would have been quite a handful.